import java.util.Scanner;
class Work3{
	public static void main(String[] args) {
		int a = nextInt();
		if (a>80&&a<=100){
			System.out.println(A);
		}else if (a>70&&a<=80){
			System.out.println(B);
		}else if (a>60&&a<=70){
			System.out.println(C);
		}else if (a>0&&a<=60){
			System.out.println(D);
		}
		
	}
}
